It has been pointed out by the theoretic model of anion coordination polyhedra of growth units that the crystal form is dominated by the stability of combination of anion coordination polyhedra on the growth interface...It has been pointed out by the theoretic model of anion coordination polyhedra of growth units that the crystal form is dominated by the stability of combination of anion coordination polyhedra on the growth interface.The face has the fastest growth rate and disappears easily if the vertex of coordination polyhedron is pointed at.The face has the slowest growth rate and appears easily if the plane of coordination polyhedron is pointed at.The growth rate is in median for the face that the edge of coordination polyhedron is pointed at.A few of problems are discussed in the paper on the basis of this theory. (1)Several examples of the morphology of allomorph and homoeomorphism are given in the paper.There are three allomorphs of TiO 2 rutile,brookite and anatase.The morphology of these allomorphs are totally different because the stability of combination of octahedral [Ti O 6] 8- vary with the orientation and linked edges of coordination polyhedra.Another example is the homoeomorphism of cassiterite SnO 2.The orientation and combination of octahedral [Sn O 6] 8- in cassiterite are similar to that of octahedral [Ti O 6] 8- in rutile,so that cassiterite and rutile have similar morphology even for their form of twin and twin face.The combination of octahedral [Al O 6] 9- ,[Fe O 6] 9- and [Ti O 6] 8- respectively is similar at the orientation and linked form of coordination polyhedra in three crystals of corundum,hematite and ilmenite,so the same faces appear in these three crystals,resulted in similar morphology.展开更多
Form error measurement is a critical exercise in providing measures for the quality control in the precision manufacturing industry.Coordinate measuring machine （CMM） is one of the automated systems used in the accu...Form error measurement is a critical exercise in providing measures for the quality control in the precision manufacturing industry.Coordinate measuring machine （CMM） is one of the automated systems used in the accurate and precise dimensional measurements and geometrical form.This paper aims to study the effect of dynamic original unforeseeable errors at different undulations per revolution （UPR） of standard artifact measurement using selected two types of CMM touchtriggering stylus.Stylus-type and stylus-speed parameters were adopted and utilized throughout the course of experiment.The results are analyzed using fast Fourier transformation to obtain foreseeable geometrical errors due to CMM machine structure and stylus scanning speeds.The results of experiment successfully indicate that the number of UPR plays an important role in determining the CMM accuracy level of the roundness measurement result.Some specific error equations for stylus system and machine structure responses have been postulated and analysed to empirically predict the accuracy of PRISMOBridge-CMM-type at National Institute for Standards （NIS） in egypt.展开更多
文摘It has been pointed out by the theoretic model of anion coordination polyhedra of growth units that the crystal form is dominated by the stability of combination of anion coordination polyhedra on the growth interface.The face has the fastest growth rate and disappears easily if the vertex of coordination polyhedron is pointed at.The face has the slowest growth rate and appears easily if the plane of coordination polyhedron is pointed at.The growth rate is in median for the face that the edge of coordination polyhedron is pointed at.A few of problems are discussed in the paper on the basis of this theory. (1)Several examples of the morphology of allomorph and homoeomorphism are given in the paper.There are three allomorphs of TiO 2 rutile,brookite and anatase.The morphology of these allomorphs are totally different because the stability of combination of octahedral [Ti O 6] 8- vary with the orientation and linked edges of coordination polyhedra.Another example is the homoeomorphism of cassiterite SnO 2.The orientation and combination of octahedral [Sn O 6] 8- in cassiterite are similar to that of octahedral [Ti O 6] 8- in rutile,so that cassiterite and rutile have similar morphology even for their form of twin and twin face.The combination of octahedral [Al O 6] 9- ,[Fe O 6] 9- and [Ti O 6] 8- respectively is similar at the orientation and linked form of coordination polyhedra in three crystals of corundum,hematite and ilmenite,so the same faces appear in these three crystals,resulted in similar morphology.
文摘Form error measurement is a critical exercise in providing measures for the quality control in the precision manufacturing industry.Coordinate measuring machine （CMM） is one of the automated systems used in the accurate and precise dimensional measurements and geometrical form.This paper aims to study the effect of dynamic original unforeseeable errors at different undulations per revolution （UPR） of standard artifact measurement using selected two types of CMM touchtriggering stylus.Stylus-type and stylus-speed parameters were adopted and utilized throughout the course of experiment.The results are analyzed using fast Fourier transformation to obtain foreseeable geometrical errors due to CMM machine structure and stylus scanning speeds.The results of experiment successfully indicate that the number of UPR plays an important role in determining the CMM accuracy level of the roundness measurement result.Some specific error equations for stylus system and machine structure responses have been postulated and analysed to empirically predict the accuracy of PRISMOBridge-CMM-type at National Institute for Standards （NIS） in egypt.
